linux-kernel - [PATCH 3.5 25/62] cpufreq: powernow-k8: Initialize per-cpu data-structures properly

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Message-Id: <1394030226-26652-26-git-send-email-luis.henriques@canonical.com>
Date:	Wed,  5 Mar 2014 14:36:29 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.5 25/62] cpufreq: powernow-k8: Initialize per-cpu data-structures properly

3.5.7.32 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>

commit c3274763bfc3bf1ececa269ed6e6c4d7ec1c3e5e upstream.

The powernow-k8 driver maintains a per-cpu data-structure called
powernow_data that is used to perform the frequency transitions.
It initializes this data structure only for the policy->cpu. So,
accesses to this data structure by other CPUs results in various
problems because they would have been uninitialized.

Specifically, if a cpu (!= policy->cpu) invokes the drivers' ->get()
function, it returns 0 as the KHz value, since its per-cpu memory
doesn't point to anything valid. This causes problems during
suspend/resume since cpufreq_update_policy() tries to enforce this
(0 KHz) as the current frequency of the CPU, and this madness gets
propagated to adjust_jiffies() as well. Eventually, lots of things
start breaking down, including the r8169 ethernet card, in one
particularly interesting case reported by Pierre Ossman.

Fix this by initializing the per-cpu data-structures of all the CPUs
in the policy appropriately.

References: https://bugzilla.kernel.org/show_bug.cgi?id=70311
Reported-by: Pierre Ossman <pierre@...man.eu>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/cpufreq/powernow-k8.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index c671369..3d26001 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -1271,7 +1271,7 @@ static int __cpuinit powernowk8_cpu_init(struct cpufreq_policy *pol)
 		FW_BUG PFX "Try again with latest BIOS.\n";
 	struct powernow_k8_data *data;
 	struct init_on_cpu init_on_cpu;
-	int rc;
+	int rc, cpu;
 	struct cpuinfo_x86 *c = &cpu_data(pol->cpu);

 	if (!cpu_online(pol->cpu))
@@ -1360,7 +1360,9 @@ static int __cpuinit powernowk8_cpu_init(struct cpufreq_policy *pol)
 		pr_debug("cpu_init done, current fid 0x%x, vid 0x%x\n",
 			data->currfid, data->currvid);

-	per_cpu(powernow_data, pol->cpu) = data;
+	/* Point all the CPUs in this policy to the same data */
+	for_each_cpu(cpu, pol->cpus)
+		per_cpu(powernow_data, cpu) = data;

 	return 0;

@@ -1375,6 +1377,7 @@ err_out:
 static int __devexit powernowk8_cpu_exit(struct cpufreq_policy *pol)
 {
 	struct powernow_k8_data *data = per_cpu(powernow_data, pol->cpu);
+	int cpu;

 	if (!data)
 		return -EINVAL;
@@ -1385,7 +1388,8 @@ static int __devexit powernowk8_cpu_exit(struct cpufreq_policy *pol)

 	kfree(data->powernow_table);
 	kfree(data);
-	per_cpu(powernow_data, pol->cpu) = NULL;
+	for_each_cpu(cpu, pol->cpus)
+		per_cpu(powernow_data, cpu) = NULL;

 	return 0;
 }
-- 
1.9.0

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